Exosomal miRNA-mRNA interactions highlight MSC-like molecular signatures in dental pulp fibroblasts

Exosomes derived from mesenchymal stem cells (MSCs) are increasingly recognized as promising mediators of tissue regeneration. However, most studies have focused on exosomes from purified MSC populations, and the regenerative relevance of exosomes secreted by fibroblast-dominant oral cell populations remains poorly understood. This study aimed to characterize the cell type-specific miRNA-mRNA regulatory features of exosomes released by gingival fibroblasts, periodontal ligament fibroblasts, and dental pulp fibroblasts, and to evaluate their potential links to MSC-like molecular programs.

Fibroblast-rich cell populations were isolated from gingiva, periodontal ligament, and dental pulp tissue from the same extracted teeth, without MSC purification. Bulk RNA-seq was performed on the cells, and exosomes were collected from culture supernatants for miRNA-seq, small RNA-seq, and RNA-seq (n = 3 donors). Cell type-specific miRNA-mRNA regulatory axes were identified based on inverse expression patterns and confirmed using experimentally validated interactions from miRTarBase.

Cellular transcriptomic profiling showed that dental pulp fibroblasts expressed higher levels of genes associated with stemness, osteogenic potential, and metabolic regulation, whereas gingival and periodontal ligament fibroblasts exhibited signatures related to inflammation, vesicle trafficking, and tissue homeostasis. Exosomal RNA profiling revealed distinct regulatory modules for each fibroblast type: gingival fibroblast-derived exosomes exhibited a miR-660-5p/XKR7 axis associated with apoptosis regulation; periodontal ligament fibroblast-derived exosomes displayed a miR-199a-5p/COL19A1 axis linked to extracellular matrix remodeling; and dental pulp fibroblast-derived exosomes contained multiple MSC-associated regulatory axes, including miR-1307-3p and miR-30b-3p targeting SNRPD1, miR-493-5p targeting HMGXB4, and miR-26b-5p targeting MB-HSPD1.

Exosomes derived from fibroblast-rich oral cell populations display distinct molecular signatures reflective of their tissue origins. Notably, exosomes from dental pulp fibroblasts exhibit MSC-like regulatory features. These findings suggest that exosomes from mixed fibroblast cultures, without requiring MSC purification, may hold promise as practical, cell-free regenerative tools, pending future functional validation.